Injuries to tissue such as cartilage, skin, muscle, bone, tendon and ligament, frequently require surgical intervention to repair the damage and facilitate healing. Surgical procedures to repair tissue damage are often performed using sutures connected to one or more anchoring device (suture anchor) implanted in or adjacent to the damaged tissue. The sutures can also be passed through or around the tissue according to a variety of surgical techniques to secure the repair. The sutures can also interconnect two or more anchors used to perform the repair. Suture anchors have been fabricated with bodies formed from a variety of materials including nonabsorbable materials such as metals and durable polymers, as well as bioabsorbable materials such as absorbable polymers, bioceramics, absorbable composites and processed bone.
Anchors can be designed for fixation with respect to tissue using external screw threads on an anchor body, an expandable body, toggling action, extendable components such as barbs, or other mechanical retention means. Sutures can be connected through or around suture anchors in a fixed or a sliding manner, for example, using eyelets or other passages in an anchor body, and can be secured using stationary or sliding knots, interference among anchor components, interference between an anchor and surrounding tissue, or other means. Some suture anchors are designed for suture to slide unidirectional through or around the anchor, enabling a surgical repair to be tightened by tensioning a portion of the suture with respect to the anchor. Among their many surgical applications, suture anchors are used with sutures to reattach damaged tendons or ligaments to bone, to tighten compromised tissue surrounding articulating joints, and to repair tears in cartilage, such as torn meniscal cartilage in a knee. In some applications, two or more anchors joined by an adjustable length of suture enable a tissue tear to be cinched closed, or compromised tissue to be stabilized.
Of great importance in suture anchor design is maximizing the retention strength of the anchor in tissue, to minimize the risk of anchor breakage or pullout from tissue when an attached suture is tensioned with respect to the anchor. One common approach to maximizing anchor retention strength is to use physically larger anchors than might be preferable to minimize surgical trauma caused by the procedure used to implant the anchor. Not only does the implantation of a larger anchor generally require a larger and therefore more traumatic surgical incision than would be required to implant a smaller anchor, but the tools required to implant or deploy a larger anchor may also be correspondingly larger. Compounding this issue, the process of deploying an anchor in tissue can require both substantially vertical access to the tissue repair site, and significantly deeper penetration into or through the tissue than the depth required to retain the anchor after deployment in tissue. In addition, many surgical anchors have sharp edges that can cause tissue damage when implanted in a patient. Addressing these concerns is particularly important in the development of minimally invasive surgeries such as arthroscopic procedures that restrict access to an operative site, at least in part to reduce surgical trauma relative to open surgical procedures.
There is a preference among some surgeons for using non-metallic suture anchors rather than metallic suture anchors. While some nonmetallic anchors can provide advantages over metallic anchors with respect to bioabsorbability or radiolucence, many nonmetallic anchors provide significantly lower mechanical strength than metallic anchors, increasing the potential for mechanical failure of the surgical repair during or post-surgery. For example, suture may cut through relatively soft materials used to fabricate a nonmetallic anchor, a process often called “cheese-wiring.” With metallic suture anchors, the interface between suture and the anchor must also be carefully designed to protect attached suture from breakage. For example, a metallic suture anchor may require precision polishing to minimize suture failure where suture contacts the much harder metal. With any suture anchor, sharp bends of suture about anchor components are well-known stress points that can lead to failure of a surgical repair. Post-surgical failure of an anchor-based surgical repair during the healing period is of particular concern because uncontrolled fragments of a failed anchor have the potential to cause injury to the patient.
Accordingly, there remains a need for improved suture anchoring devices, systems and methods for repairing damaged tissue that overcome the limitations and disadvantages of known suture anchors. A need also exists for suture anchors, deployment tools and methods that minimize the surgical trauma associated with the implantation of an anchor of any given size.